In various fields of industries, automatic ice making machines which make ice cubes having a regular hexahedral shape, ice plates having a predetermined thickness or ice cakes or blocks of other shapes are suitably utilized depending on the purpose. For example, as the above ice making machine for making ice cubes, known are:
(1) a so-called closed cell system ice making machine, in which a plurality of cubic freezing cells defined to open downward in a freezing chamber is closed with a water tray which is descendable, such that the water to be frozen may be injected into each freezing cell from the water tray to form ice cubes gradually in the freezing cells; and PA1 (2) a so-called open cell system ice making machine, in which a water to be frozen is directly fed into a plurality of freezing cells which opens downward without using a water tray to form ice cubes in the freezing cells.
On the other hand, as the ice making machine for making ice plates continuously, widely used are those of flow-down system in which a freezing plate equipped with an evaporator connected to a freezing system is disposed to form a slant plane, and a water to be frozen is supplied to flow over the upper or lower surface of this freezing plate to form an ice plate over the surface of the freezing plate. Further, there is practically employed an ice making system for obtaining ice flakes, in which water is allowed to flow down along the internal wall surface of a freezing cylinder to form an ice layer, which is scratched with a cutting blade of a rotary auger, or for obtaining granular crushed ice by crushing the ice plate obtained from the aforementioned ice making machine.
As described above, the ice which can be made by any of the automatic ice making machines according to the conventional methods have been limited to cubic ice cakes, ice plates, ice flakes and crushed ice. Among these types of ice, those which have a certain shape and can be used as such directly, for cooling a glass of drink or as a cooling bed for various food materials, are only limited to the ice cubes mentioned above (although ice plates may be made to have a fixed shape, they are usually unusable as such with their original sizes). Therefore, in coffee shops, restaurants and other food service shops, earnest efforts are made recently to be distinguished from and to emulate others which offer the same type of service. As a part of such efforts, for example, there is a tendency in some shops to use ice balls instead of ice cubes which have conventionally been used widely, to treat customers with something new or a change.
As a means for making such ice balls, as shown, for example, in Japanese Provisional Utility Model Publication No. 60177/1983, there is known an ice tray composed of a tray in which a suitable number of concaves having an arbitrary shape have been formed and a removable cover having concaves corresponding to the recesses of the tray. In this ice tray, spherical ice cakes are obtained by introducing water into the spherical spaces defined by these concaves and placing the ice tray containing the water in the freezer of a refrigerator for a predetermined time to allow the water contained in the spherical spaces to be frozen. Further, some attempts are made, for example, to introduce water into a bag made of an elastic film such as a rubber sheet, which is placed in the freezer or immersed in an anti-freezing solution as a cold medium to form ice balls; or to cut an ice block with a cutter into ice balls.
However, the methods of making ice balls by use of the means described above cannot afford a large amount of ice balls continuously, but require troublesome handling and time inefficiently, so that they cannot be employed for business purposes. Moreover, since ice cakes are made by causing the water to freeze statically in a freezer or in an antifreezing solution in the above methods, the ice cakes obtained are opacified with the very small amount of air contained in the water. Therefore, the above methods involve disadvantage that no clear and transparent ice cakes can be obtained, resulting in reduced commercial value. Thus, under the present circumstances when there is an increasing demand for such machines, no such machine which can make a large amount of uniform and transparent ice balls or polyhedral ice cakes continuously has yet been utilized practically.